Radio telephone monitoring system



G. RpwlN 2,092,474 RADIO TELEPHONE MONTORING SYSTEM Filed Dee. 9, 195e 2 sheets-sheet 1` Sept. 7, '1937.

/NVE/VTOR G. RODW/N BV ATTORNEY sept. 7, 1937. G, RODWW 2,092,474

RADIO TELEPHONE MONITORING SYSTEM Filed Deo. 9, 1936 ZSheeS-Sheet. 2

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MPL/HER osrfcron Hr AMP 2?/ um /sT an mp1. /f/En persero# /Nl/ENTOR G. RODW/N ATTORNEY Patented Sept. 7, 1937 RADIO TELEPHONE MONITORING SYSTEM George Rodwin, Randall Manor, N. Y., assigner to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application December 9, 1936, Serial No. 114,908

11 Claims. (Cl. Z50-20) This invention relates to radio telephone circuits and more particularly to facilities for enabling monitoring to be accomplished on a plurality of radio telephone receiving channels which are used on a shared time basis.

Mln some instances it is desirable to use one receiver for monitoring on any one of a plurality of receiving channels each served by a different directive antenna. Each of the channels may be arranged, for example, to receive on a different lcarrier frequency band and to be connected to.

any one of a plurality of intermediate frequency service channels. Since the receiving channels are used on a shared time basis it is not necessary to provide an intermediate frequency service channel individual to each receiving channel but only as many service channels as are found necesenabling the monitoring operato-r to manually connect any one of a plurality of receiving chan-` nels, vuponwhich reception has been detected, to any one of a plurality of service channels. It is the object of the present invention to render the connection of the receiving channels to availn able'service channels entirely automatic.

'While one mannerin which this object may be attained is disclosed herein, it is to be understood that the disclosure is only illustrative of one embodiment of the invention and that other equivalent circuits and apparatus might be employed without departing from the scope of the inventionas deiined in the appended claims.

In accordance with the invention provision is made for monitoring by a sin-gie receiver on any one -of a plurality of receiving channels each associated with a receiving antenna. Each receiving channel comprises high frequency amplier and iirst detector panels tuned to receive on a particular high frequency band. The carrier bands transmitted from different stations may be modulated by tone signals of relatively low frequency by means of which each transmitting station may be distinctively identied. Thus, for

example,v four transmitting stations could be identified by four modulating tone frequencies of 600,` 1050, 1500 and 1950 cycles, respectively.

In accordance with the invention, each high frequency channel has `associated therewith a filter circuit tuned to respond to the modulating tone signal which is indicative that reception is incoming on that channel, a secondary amplifier and detector panel and a tone relay which is responsive if the associated filter passes `the distinctive tone signal. Four intermediate frequency receiving channels are also provided three quency channel is connected to the input side ofthe intermediate frequency monitoring channel and theoutput side of the monitoring channel isconnected to the filters associated with all of the high frequency receiving channels. A group of switching relays is allotted to each high frequency receiving channel comprising as many relays as there are intermediate frequencyf A second group of sequence A.

service channels. relays, comprising a relay for each service channel, is also associated with each high frequency receiving channel, the corresponding sequence relays of all of the groups being arranged to be operated in parallel.v WheneverV any receivingl channel is switched into connection with the service channel to which they are allotted.

Briefly the invention functions in the follow-1 If, for example, the tone relay ing manner: associated with the `irst vreceiving channel becomes operated, indicating reception on that channel, and all service channels are at the time available, the tone relay in conjunction with the sequence relays associated with that channel will cause the Voperation of the rst switching relay of the group associated with the rst receiving channel to switch the first channel from the monitoring channel to the irst service channel and to `operate the iirst sequencerelay of each group of sequence relays. The operation of these sequence relays bars the connection of another receiving channel to the first service channel and prepares the circuits for connecting another one of the receiving channels to the next available 40 Should the tone relay associated with the sec?y ond `receiving channel now become operated, it

service channel.

ceiving channel to the second service channel and prepares the circuits for connecting another one of the receiving channels to the next available service channel. Other receiving channels are connected to available service channels in the same manner.

It is believed that a clearer understanding of the invention and its mode of operation may be obtained from a consideration of the following detailed description taken in connection with the accompanying drawings of which:

Figs. 1 and 2 taken together with Fig. 2 placed beneath Fig. l, show one embodiment of the invention, Fig. 1 showing one high frequency receiving channel and the switching equipment associated therewith and the intermediate frequency monitoring and service channels; and Fig. 2 showing additional high frequency receiving channels and the switching equipment thereof.

It is to be understood that although in order to simplify the disclosure only three high frequency receiving channels and three intermediate frequency service channels have been illustrated, as many other high frequency channels would be supplied as might be found necessary to receive transmission from other transmitting stations and as many other service channels would be supplied as might be found necessary to handle the traffic load.

Referring to the drawings, it will be assumed that monitoring on three high frequency receiving channels is required, these high frequency channels being schematically illustrated by the boxes 0| 20| and 22| and each comprising a receiving antenna system, a high frequency amplifier panel and a first detector panel. Also associated with each high frequency channel is a filter circuit, a tone signal amplifier panel and a tone signal detector panel. The filter circuits are disclosed schematically by the boxes 02, 202 and 222 and the amplifier and detector panels by the boxes |03, 203 and 223.

Four intermediate frequency receiving channels H3, H4, H5 and H6 are provided each comprising an intermediate frequency amplifier, second detector, audio frequency amplifier and power unit as indicated by the boxes. One of these channels H3 serves as a monitoring channel and is normally connected on its input side in parallel to the output side of each of the high frequency receiving channels and on its output side to a suitable monitoring device such as a loud speaker and in parallel to the filter circuits associated with all of the high frequency receiving channels. The other three intermediate frequency channels H4, H5, and H6 are connected on their output sides to service channels.

Associated with each high frequency channel are a tone relay, two control relays, a group of three switching relays and a group of three sequence relays. The switching relays are effective when operated to connect the output side of the particular channel with the input side of any one of the three intermediate frequency service channels H4, H5 and H6 and at the same time to dissociate the particular channel from the monitoring channel. For example, relay |01 when operated, connects channel |0| to service channel H4; relay |09 when operated, connects channel |0| to service channel H5; and relay H| when operated, connects channel |0| to service channel H6. Similarly relay 201 is effective to connect channel 20| to service channel H4; relay 209 is effective to connect channel 20| to service channel H5; and relay 2H is effective to connect channel 20| to service channel H6.

The group of sequence relays associated with each high frequency receiving channel serves to bar the connection of a second high frequency channel to any service channel to which another high frequency channel is at the time connected. The sequence relays of each group are paired with the switching relays of the same high frequency channel and corresponding relays of all of the groups of sequence relays are arranged to be operated in parallel. For example the sequence relay |08 is paired with switching relay |01 and is operated in parallel with the corresponding sequence relays 200 and 228 of the other groups when any one of the switching relays |01, 201 or 221 is operated to connect one of the high frequency channels with service channel H4. Similarly, sequence relay H0 is paired with switching relay |09 and is operated in parallel with the corresponding sequence relays 2|0 and l230 of the other groups when any one of the switching relays |09, 209 or 220 is operated to connect one of the high frequency channels with service channel H5.

Having now described the apparatus of the monitoring system, the manner in which it functions will now be described. It will be assumed that all of the service channels are available for use and that all of the switching relays are therefore unoperated. The output side of high frequency receiving channel |0| is therefore connected over the outer left back contact of relay |05 to conductor H1 and thence to the input side of the monitoring channel H3 and the output side of the monitoring channel is connected over conductor H8, thence in series over the inner right back contacts of switching relays H I, |09 and |01 to the filter circuit |02; the output side of the high frequency receiving channel 20| is connected over the outer left back contact of relay 205 to conductor H1 and thence to the input side of monitoring channel H3 and the output side of the monitoring channel is connected over conductor H8, thence in series over the inner right back contacts of switching relays 2| 209 and 20'! to the filter circuit 202; and the output side of the high frequency receiving channel 22| is connected over the outer left back Contact of relay 225 to conductor H1 and thence to the input side of monitoring channel H3 and the output side of the monitoring channel is connected over conductor H8, thence in series over the inner right back contacts of switching relays 23|, 229 and 221 to the filter circuit 222. Thus normally, the monitoring channel H3 is connected in parallel to each of the high frequency receiving channels and to each of the filter circuits associated therewith.

It will now be assumed that reception is incoming on the high frequency receiving channel |0| and that the modulating tone signal incoming thereover is detected and impressed on the monitoring operators monitoring device and upon the filter circuit |02 which is tuned to pass only a tone signal of the frequency incoming over receiving channel |0|. 'The filter circuits 202 and 222 associated with the other receiving channels 20| and 22| will not pass this tone signaling frequency. The monitoring operator hearing the distinctive tone signal is now apprised of the fact that reception is incoming over the first receiving channel |0|.

Since the filter circuit |02 passes this tone signaling frequency, the amplifier and detector circuits |03 respond to cause the operation of tone relay |04 which establishes a circuit from ground at its contacts over the inner left normal contacts and winding of relay |05 through resistance ||9 to battery on bus-bar |20 and in parallel through the winding of relay and resistance |00 to battery on bus-bar |20. Relay |05 thereupon operates and locks over its inner left alternate contacts to ground. Relay |00 does not operate at this time since its winding is shunted over its own back contact to ground at the contacts of relay |04 so long as relay |04 remains operated in response to the incoming tone signal.

Relay upon operating establishes an operating circuit for switching relay |01 extending from battery through the winding ci relay |01, back contact of the sequence relay |00 paired therewith, to ground at the inner right front contact of relay |05 and a locking circuit for switching relay |01 which is effective as soon as relay |01 operates extending from battery through the winding and inner left front contact of relay |01 to ground at the outer right front contact of relay |05. At its outer left back contact `relay |05 disconnects the output sid-e of the receiving channel |0| from the monitoring channel ||3 and at its outer left front contact connects the output side of the receiving channel |0| over the outer left front Contact of switching relay |01, now operated, to conductor |22 and thence to the input side of the first intermediate frequency service channel H0. The modulating tone signal is now impressed upon the service channel ||l| and from the output side thereof over conductor |23, the inner right front contact of switching relay |01 to the lter circuit |02 thereby maintaining the tone relay |00 voperated so long as the tone signal persists. Relay |00 is made slightly slow to release in order that it may hold its contacts closed until after relay |01 has operated.

Relay |01 at its middle left iront contact connects ground to conductor thereby establishing parallel operating circuits through the windings of sequence relays |00, 200 and 220 to battery on the bus-bar |20. Relay |00 upon operating opens the initial operating circuit of switching relay |01 and prepares the operating circuit for switching relay |00, but, since switching relay |01 is operated, the circuit ofrelay |00 is open at the outer right back contact of relay |01. Sequence relay 200 upon operating opens at its back contact vthe operating circuit of switching relay 201 and at its front contact prepares the op erating circuit of switching relay 200.. Similarly sequence relay 228 opens at its back contact the operating circuit of switching relay 221 `and at its front contact prepares the operating circuit of switching relay 229. Thus the operation of the sequence relays 208 and 228 bars the connection of another high frequency receiving channel to the service channel i0 and allots the-next service channel ||5 for connection to another high frequency channel.

Upon the discontinuance of the tone signal, tone relay |04 releases thereby removing the shunt from the winding of` relay |00 which thereupon operates in a circuit from battery on busbar |20, resistance |00, winding of relay |00, inner left alternate contacts of relay |05 to ground. Relays |05, |00, |01, |00, 200 and 220 now remain operated during the continuance of reception over the high frequency receiving channel |0|.

When the transmitting station desires to discontinue transmission, the modulating tone signal is again transmitted, is received in the service channel ||l| and is passed by the llter circuit |02 tol cause the reoperation of tone relay I 01|.

Relay |04 upon operating connects ground over its contacts and the front contact of relay |06 to a point between resistance l0 and the winding of relay |05 thereby shunting the winding of relay |05 which thereupon releases. Following the release of relay |05, relay |00 is maintained operated so long as the tone relay |04 is operated in a locking circuit extending from ground over the contactsof relay |00, the normal contacts of relay |05, winding of relay |00, resistance |00 to battery on bus-bar |20. Relay |05 upon releasing also opens the locking circuit of switching relay |01 and theV operating circuits of sequence relays |08, 200 and 228 which now release, relay |017 upon releasing disconnecting the receiving channel |0| from the service channel I0. Upon the discontinuance of the tone signal, relay |00 releases in turn releasing relay |00. The circuits are now in their normal condition.

It will now be assumed that while reception is being received over the high frequency channel l0! and service channel H0, at which timek switching relay |01 and sequence relays |00, 208 and 220 are operated as previously described, reception is received on the high frequency channel 20|, the output side of which is associated with the input side of the monitoring channel i I3 over the outer left back contact of relay 205 and conductor ||1. The modulating tone signal will now be detected in the monitoring channel apprising the monitoring operator that reception is being received and the signaling tone will be impressed frorn the output side of the monitoring channel ||3, over conductor |0, in series over the inner right back contacts of switching relays 2||, 200 and 201 uponathe iilter circuit 202. Filter circuit 202 will pass the tone signal whereupon the detector and amplier circuits 203 will respond tolcause the operation of tone relay 204. The tone signal will also be impressed upon iilter circuit 222 over conductor i8 and the inner right backcontacts of switching relays 23|, 220 and 221 but without effect since filter circuit 222 is so tuned as not tol pass the signaling tone received over either channel |0| or channel 20|. With switching relay |01 operated as assumed, the tone signal does not reach filter circuit |02.

Relay 204 upon operating now establishes a circuit from ground over its contacts, the inner left normal contacts and winding oi' relay 205, resistance 2|9 to battery on bus-bar |20 and in parallel through the winding of relay 205 and resistance 200 to battery on bus-bar |20. Relay 205 thereupon operates and locks over its inner left alternate contacts to ground, but relay 206 does not operate since its winding is shunted in a circuit extending over its own back contact so long as relay 200 remains operated in response to the incoming tone signal.

With relay 205 and sequence relay 200 both operated, the operating circuit of switching relay 209 is established and may be traced from battery on bus-bar |20, winding of relay 209, back contact of sequence relay 2|0, outer right back contact of switching relay 201, front contact of sequence relay 200 to ground at the inner right contact of relay 205. Relay 200upon operating now locks over its inner left front contact to ground at the outer right front Contact of relay 205. At its outer left back contact, relay 205 disconnects the output side of the receiving channel 20| from the monitoring channel ||3 and at its outer left front contact connects the output side of receiving channel 20| over the outer left front contact of switching relay 200,

now operated, conductor |25 and thence to the second intermediate frequency service channel ||5. The modulating tone signal is now impressed On the service channel ||5 and from the output side thereof over conductor |26, the inner right front Contact of switching relay 209, the inner right back contact of switching relay 207 to the llter circuit 202 thereby maintaining the tone relay 204 operated so long as the tone signal persists.

Relay 229 at its middle left front Contact connects ground to conductor |2'| thereby establishing parallel operating circuits through the windings of sequence relays H0, 2|0 and 230 to battery on bus-bar |20. Relay 2|Ei upon operating opens the initial operating circuit of switching relay 209 and prepares the operating circuit for switching relay 2| I, but, since switching relay 209 is operated, the circuit of relay 2|| is open at the outer right back contact of relay 209. Sequence relay H0 upon operating opens at its back contact the operating circuit of switching relay E09 and at its front contact prepares the operating circuit of switching relay I I Similarly, sequence relay 230 opens at its back contact the operating circuit of switching relay 220 and at its front contact prepares the operating circuit oi switching relay 23|. Thus the operation of sequence relays ||0 and 230 bars the connection of any other high frequency receiving channel to the service channel H5 and allots the next service channel I6 for connection to another high frequency channel.

Upon the discontinuance of the tone signal over receiving channel 20|, relay 204 releases thereby removing the shunt from-the winding of relay 200 which thereupon operates in a circuit from battery on bus-bar 20, resistance 200, winding of relay |06, inner left alternate contacts of relay 205 to ground. Relays 205, 206, 209, H0, 2|0, and 230 now remain operated during the continuance of reception over channel 20|. When the transmitting station desires to discontinue transmission, the tone signal is again transmitted, is received in the service channel ||5 and is passed by the filter circuit 202 to cause the reoperation of tone relay 204. Relay 204 upon operating connects ground over its contacts and the front contact of relay 200 to a point between resistance 2i9 and the winding of relay 205 thereby shunting the winding of relay 205 which thereupon releases. Following the release of relay 205, relay 206 is maintained operated so long as tone relay 205i is operated in a locking circuit extending from ground over the contacts of relay 204, the normal contacts of relay 205, winding of relay 200, resistance 200 to battery on bus-bar |20. Relay 205 upon releasing also opens the locking circuit of switching relay 209 and the operating circuits of sequence relays l0, 2|0 and 230 which now release. Relay 209 upon releasing disconnects the receiving channel 20| from the service channel H5. Upon the discontinuance of the tone signal, relay 204 releases in turn releasing relay 200.

Should reception now be received on the high frequency channel 22| with both Service channels H4 and ||5 in use, channel 22| will become connected to the third service channel ||6 through the operation of relays 225, 220 and the switching relay 23| in a similar manner. It will, however, be assumed that at the time reception is received on channel 22|, the second service channel H5 has again become available but that the rst service channel H4 is unavailable. When relays 224 and 225 operate, with sequence relay 228 still operated and sequence relay 230 released, the circuit of switching relay 229 is established from battery on bus-bar |20, winding of relay 229, back contact of sequence relay 230, outer right back contact of switching relay 221, front Contact of sequence relay 228 to ground at the inner right front contact of relay 225. Relay 229 upon operating locks over its inner left front contact to ground at the outer right contact of relay 225, connects the output side of channel 22| over its outer left front contact and conductor |25 to the input side of service channel I5 and over its middle left front contact establishes parallel operating circuits for sequence relays ||0, 2|0 and 230. These sequence relays thereupon operate and function as previously described to bar the connection of another high frequency receiving channel to the service channel ||5 and to prepare circuits for allotting the next service channel l l0 for use on the next call.

From the foregoing description, it will be apparent that the monitoring circuits are entirely automatic in their operation and that the monitoring operator is not required to perform any manual switching operations to associate high frequency receiving channels on which reception is present to available intermediate frequency service channels and is therefore enabled to devote his entire attention to the adjustment of the control apparatus of the channels for the best reception.

What is claimed is:

l. In a signaling system, a plurality of high frequency receiving channels, a monitoring channel, said monitoring channel being normally connected with each of said receiving channels, a plurality of intermediate frequency service channels, means for switching any one of said receiving channels from connection with said monitoring channel into connection with any one of said service channels, and means responsive to reception on any one of said receiving channels to operate said switching means.

2. In a signaling system, a plurality of high frequency receiving channels, a monitoring channel, said monitoring channel being normally connected with each of said receiving channels, a plur-ality of intermediate frequency service channels, means ior switching any one of said receiving channels from connection with said monitoring channel into connection with any one of said service channels, means for allotting said service channels for use, and means responsive to reception on any one of said receiving channels to operate said switching means to connect said receiving channel to an allotted one of said service channels.

3. In a signaling system, a plurality of high frequency receiving channels, means associated with each of said channels responsive respectively to a different signaling frequency, la monitoring channel, said monitoring channel being normally connected with each of said receiving channels and with each of said associ-ated responsive means, a plurality of intermediate frequency service channels, and means for switching any one of said receiving channels and associated responsive means from connection with said monitoring channel into connection with any one oi said service channels, said switching means being controlled by the responsive means of a receiving channel when reception is present on such channel.

4. In a signaling system, a plurality of high frequency receiving channels, means associated with each of said channels responsive respectively to a different signaling frequency, a `monitoring channel, said monitoring channel being normally 5 connected with each of said receiving channels i and with each of said associated responsive means, a plurality of intermediate frequency service channels, means for switching any one of said receiving channels and associated responsive l means from connection with said monitoring channel into connection with any one of said service channels, means for allotting said service "chan-nels for use, and means controlled by the responsive means of a receiving channel when rel ception is present on such channel to operate said switching means to connect said receiving channel to an allotted one of said service channels.

5. In a signaling system, a plurality of high frequency receiving channels, means associated with each of said channels responsive respectively to a different signaling frequency, a monitoring channel, said monitoring channel being normally connected on its input side to each of said receiving channels and on its output side to each of 95 said responsive means, a plurality of intermediate frequency service channels, a group of switching relays associated with each of said receiving channels, each relay of a group being individualized to a different one of said service channels, and means controlled by the responsive means of a receiving channel on which reception is present to disconnect said channel from the input sideof said monitoring channel and to operate one of said switching relays to connect said receiving channel to the input side of a service channel and to transfer the connection of the responsive means of said receiving channel from the output side of said monitoring channel to the output side of said service channel.

6. In a signaling system, a plurality of high frequency receiving channels, means associated with each of said channels responsive respectively to a different signaling frequency, a monitoring channel, said monitoring channel being normally connected with each of said receiving channels and with each of said associated responsive means, a plurality of intermediate frequency service channels, means for switching any one of said receiving channels and associated responsive means from connection withsaid monitoring channel into connection with any one of said service channels, said switching means being controlled by the responsive means of the receiving channel when reception is present on such channel, and

means controlled by the responsive means of the receiving channel which has been connected with a servicechannel for releasing said switching means when transmission is to be terminated.

'7. In a signaling system, a plurality of high frequency receiving channels, means associated with each of said channels responsive respectively to a different signaling frequency, a monitoring channel, said monitoring channel being normally connected on its input side to each of said receiving channels and on its output side to each of said responsive means, a plurality of intermediate frequency service channels, means for switching any one of said receiving channels and associated responsive means from connection with said monitoring channel into connection respectively with the input and output sides of any one of said service channels, said switching means being controlled by the responsive means of a receiving channel when reception is present on such channel, and means controlled by the responsive means of a receiving channel which has been connected with a service channel for releasing said switching means when transmission is to be terminated.

8. In a signaling system, a plurality of high frequency receiving channels, means associated with each of said channels responsive respectively to a different signaling frequency, a monitoring channel, said monitoring channel being normally connected with each of said receiving channels and with cach of said associated responsive means, a plurality of intermediate frequency service channels, means for switching any one of said receiving channels and associated responsive means from connection with said monitoring channel into connection with any one of said service channels, means for allotting said service channels for use, and means controlled by the responsive means of a receiving channel when reception is present on such channel to operate said switching means to connect said receiving channel to an allotted one of said service channels and to operate said allotting means to bar the connection of another receiving channel to said connected service channel and to allot another service channel for use.

9. In a signaling system, a plurality of high frequency receiving channels, means associated with each of said channels responsive respectively to a different signaling frequency, a monitoring channel, said monitoring channel being normally connected with each of said receiving channels and with each of said associated responsive means, a plurality of intermediate frequency service channels, a group of switching relays and a group of sequence relays associated with each receiving channel, one relay of each group being individualized to a different one of said service channels, means controlled by the responsive means of a receiving channel on which reception is present to disconnect said receiving channel from said monitoring channel and to operate the switching relay of the group associated with such receiving channel which is individual to an available service channel to connect said receiving channel to said available service channel and to transfer the responsive means of said receiving channel from said monitoring channel to said service channel, and means controlled by said operated switching relay for operating the sequence relays of all groups individual to the connected service channel to bar the connection of another receiving channel to said connected service channel and to allot another service channel for use.

10. In a signaling system, a plurality of high frequency receiving channels, a tuned circuit and a tone relay responsive thereto associated with each receiving channel, said circuits being tuned to be responsive to different signaling frequencies, a plurality of intermediate frequency service channels, a group of switching relays and a group of sequence relays associated with each receiving channel, one relay of each group being individualized to a different one of said service channels, means controlled by the tone relay of a receiving channel on which reception is present to operate the switching relay of the group associated with such receiving channel which is individual to an available service channel to connect said receiving channel to said available service channel, and means controlled by said operated switching relay for operating the sequence relays of all groups individual to the connected service channel to bar the connection of another receiving channel to said connected service channel and to allot another service channel for use.

11. In a signaling system, a plurality of high frequency receiving channels, a tuned circuit and a tone relay responsive thereto associated with each receiving channel, said circuits being tuned to be responsive to different signaling frequencies, a monitoring channel, said monitoring channel being normally connected with each of said receiving channels and with each of said asscciated tuned circuits, a plurality of intermediate frequency service channels, a group of switching relays and a group of sequence relays associated with each receiving channel, one relay of each group being individualized to a different one of said service channels, means controlled by the tone relay of a receiving channel on which reception is present to disconnect said receiving channel from said monitoring channel and to operate the switching relay of the group associated with such receiving channel which is individual to an available service channel to connect said receiving channel to such available service channel and to transfer the tuned circuit of said receiving channel from said monitoring channel to said service channel, and means controlled by said operated switching relay for operating the sequence relays of all groups individual to the connected service channel to bar the connection of another receiving channel to said connected service channel and to allot another service channel for use.

GEORGE RODWIN. 

